Nearly all POS systems have a way for you to export a spreadsheet with your pricing information.
Simply run a report from your system with just two columns of data: UPC and Price. If your POS does not allow you to specify which columns to export, export all columns and use Excel (or similar) to label two of the columns UPC and Price.
If you cannot see an easy way to do this on your POS system, you should contact your POS provider.
You don't need to worry about whether your products are in stock or not, as we will only display products that are in stock. To see information on downloading a spreadsheet from a detailed list of point of sale systems, view this Help content.